From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E21CEC433F5 for ; Fri, 7 Sep 2018 00:21:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A43D02075B for ; Fri, 7 Sep 2018 00:21:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A43D02075B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=codethink.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728067AbeIGE72 (ORCPT ); Fri, 7 Sep 2018 00:59:28 -0400 Received: from imap1.codethink.co.uk ([176.9.8.82]:58111 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725921AbeIGE72 (ORCPT ); Fri, 7 Sep 2018 00:59:28 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126] helo=xylophone) by imap1.codethink.co.uk with esmtpsa (Exim 4.84_2 #1 (Debian)) id 1fy4WZ-00057W-OL; Fri, 07 Sep 2018 01:21:23 +0100 Message-ID: <1536279682.3024.95.camel@codethink.co.uk> Subject: Re: [PATCH 4.4 105/124] xen-netfront: wait xenbus state change when load module manually From: Ben Hutchings To: Xiao Liang Cc: stable@vger.kernel.org, "David S. Miller" , Greg Kroah-Hartman , LKML Date: Fri, 07 Sep 2018 01:21:22 +0100 In-Reply-To: <20180804082706.393252081@linuxfoundation.org> References: <20180804082702.434482435@linuxfoundation.org> <20180804082706.393252081@linuxfoundation.org> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2018-08-04 at 11:01 +0200, Greg Kroah-Hartman wrote: > 4.4-stable review patch.  If anyone has any objections, please let me know. > > ------------------ > > From: Xiao Liang > > [ Upstream commit 822fb18a82abaf4ee7058793d95d340f5dab7bfc ] > > When loading module manually, after call xenbus_switch_state to initializes > the state of the netfront device, the driver state did not change so fast > that may lead no dev created in latest kernel. This patch adds wait to make > sure xenbus knows the driver is not in closed/unknown state. [...] > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -86,6 +86,7 @@ struct netfront_cb { >  /* IRQ name is queue name with "-tx" or "-rx" appended */ >  #define IRQ_NAME_SIZE (QUEUE_NAME_SIZE + 3) >   > +static DECLARE_WAIT_QUEUE_HEAD(module_load_q); >  static DECLARE_WAIT_QUEUE_HEAD(module_unload_q); >   >  struct netfront_stats { > @@ -1335,6 +1336,11 @@ static struct net_device *xennet_create_ >   netif_carrier_off(netdev); >   >   xenbus_switch_state(dev, XenbusStateInitialising); > + wait_event(module_load_q, > +    xenbus_read_driver_state(dev->otherend) != > +    XenbusStateClosed && > +    xenbus_read_driver_state(dev->otherend) != > +    XenbusStateUnknown); >   return netdev; >   >   exit: This won't work; it will hang. Something (maybe netback_changed()?) needs to wake up tasks on the module_load_q. Ben. -- Ben Hutchings, Software Developer   Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom